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Help with EI Calcs please.

Hi all,
Christian Walker said:
The MGSO4 = 3 tsp x 4 = 12 tsp for my tank based on the EI article. Compared to 6tsp based on the APF calculation.
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It may be because one calculation is using MgSO4 ("anhydrous"), and the other is using MgSO4.7H2O ("heptahydrate").

Whatever it says on the container it will be the "heptahydrate" form when you use it, because it will pick up atmospheric water. It makes quite a big difference to the % of magnesium in the salt.

cheers Darrel
 
Rahms said:
the EI thread gives it in terms of 20 gal, just double it and be done! I'm fairly certain its what most people on the forums will be using, so there's no need to doubt it.

edit: that said, it looks like you've doubled 1/16 to get 3/16? 😛 (KH2PO4)
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Thanks Rahms, you are quite right, I have done a slight transposition on the Potassium Phosphate. Thanks... see thats what I was after... someone to check my maths. Im more than happy to trust Clive's EI article. Its my maths thats dodgy ! lol
 
dw1305 said:
Hi all, It may be because one calculation is using MgSO4 ("anhydrous"), and the other is using MgSO4.7H2O ("heptahydrate").

Whatever it says on the container it will be the "heptahydrate" form when you use it, because it will pick up atmospheric water. It makes quite a big difference to the % of magnesium in the salt.

cheers Darrel
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OK, I will take your word on that Darrel, the salts I have are from Fluid Sensor. Its labelled as MgSO4. What is the difference between anhydrous and heptahydrate please ? I presume that Clive's EI article would take that into account and refers to the latter ?
 
Hi all,
Christian Walker said:
What is the difference between anhydrous and heptahydrate please ?
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It is the "water of crystallization", if a salt doesn't contain any water it is "anhydrous". In the case of magnesium sulphate anhydrous it is "hygroscopic", with the stable form of the salt absorbing "7H2O" to become "Epsom Salts". If you heat "Epsom Salts" you can drive off the water to give MgSO4 anhydrous but, unless you keep it in a desiccator, it will pick up atmospheric water until it becomes fully hydrated again.

When you work out the percentage magnesium (Mg) you need to know the relative molecular mass (RMM) of the salt, by adding together the relative atomic mass (RAM) of the elements.

RAM
Mg = 24
S = 32
O = 16
H = 1

MgSO4 (anhydrous) = 24+32+(4*16) RMM = 120 and the %Mg = 24/120, so it contains ~ 20% Mg.

Add in the "water of crystallization" and you add 14 hydrogen (H) atoms and 7 (O) oxygen atoms :
24+32+(4*16) + (14*1)+(7*16) ~ 24+32+64 = 120 + 14+112= 126 ~ 120 + 126 = 246 (this is the RMM "Relative Molecular Mass" of MgSO4.7H2O)

So "Epsom Salts" have 24/246 ~ 10% Mg.

cheers Darrel
 
Hi Darrel, thanks for that explanation... I managed to follow that.

It still does not explain why the proportions of MgSO4 by the aquarium online formula suggested by Ian M, in whatever state, is only half that of the figure in ceg's EI article. Unless ceg is assuming the use of anhydrous, and aquarium online are assuming the use of heptahydrate.

Im going to follow the aquarium online formula I think, especially since I am not using RO water. But it would be useful for clarification within the article. (It could be there but I missed it I suppose, but I don't recall anything that specific).

Either way, this stuff is interesting for sure.
 
Hi all,
Christian Walker said:
It still does not explain why the proportions of MgSO4 by the aquarium online formula suggested by Ian M, in whatever state, is only half that of the figure in ceg's EI article. Unless ceg is assuming the use of anhydrous, and aquarium online are assuming the use of heptahydrate.
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Could be, but I don't think it really matters, it is like "Itsai" posts, if you have some, you probably have enough. Again if you have "too much" it really doesn't matter, it isn't toxic, it doesn't cost much and if you are adding EI you aren't too concerned by raised hardness or conductivity.
ltsai said:
Don't forget Mg is a micro. May not be needed unless you are using RO water.
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True it is a micro-element, but most UK water supplies don't actually contain much Mg, this is just to do with geology.

The situation is different in the USA where a lot of the limestone aquifers have undergone <"dolomitisation">, where some proportion of the calcium in CaCO3 has been replaced by magnesium, and they often assume that the plants Mg requirement will be supplied by the water supply.

cheers Darrel


.
 
Darrel your comment about not being worried about raised hardness is interesting. How might one keep a planted aquarium in such a way that hardness does not get significantly increased ? I would like to keep some Apistogrammas and they tend to be happier in water that is not too hard.
 
Hi
Good afternoon from Singapore.🙂
Doesn't that mean one less dose of trace?
aquariumplantfood.co.uk says to dose 3 times per week for both Macro & Micro and 1 rest day.
I checked out both aquariumplantfood.co.uk and TNC's trace salts and the mixture is the same.
Maybe the difference is in the amount per dose. Maybe?
Cheers.

BTW If I can 2 rest days, all the more better.:thumbup:
 
Hi all,
Christian Walker said:
How might one keep a planted aquarium in such a way that hardness does not get significantly increased ? I would like to keep some Apistogrammas and they tend to be happier in water that is not too hard.
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I keep planted tanks with Apistogramma. I haven't tried any of the real black water species, but I've had plenty of fry from Apistogramma cacatuoides and A. agassizii. I only have "easy" plants, and all my tanks are jungles.

I have hard tap water, so I use rain-water for the tanks. All the tanks are low tech. and I feed the plants via the "Duckweed Index". There is more <"in your thread from 2013">.

cheers Darrel
 
Thanks Darrel... how do you ensure the rainwater is clear of any nasties ? Im not sure I trust my roof to be clean. Any pics of one of your apisto tanks please ?
 
Hi all,
Christian Walker said:
how do you ensure the rainwater is clear of any nasties ?
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I've used rain-water without any problems since the 1970's, but I've also got a KISS method of testing the rain-water for agricultural pollutants etc, it is the <"Daphnia bioassay"> it just means you have Daphnia in the water butt, and as long as there are swimming Daphnia in the water you draw off its OK to use.

I've got some agassizii at the moment, this is a spare sub adult male. I don't see my breeding male very often, but he is a stunner.
IMG_0042_2_zps6ojs6zbu.jpg

I've got some Apistogramma pictures in these threads: <"Apistogramma cacatuoides">.

The "best" dwarf cichlids I've kept were Dicrossus maculatus, but that ended <"in tears">.

cheers Darrel
 
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